initial commit

cmd/importTeilnehmer/main.go

@@ -0,0 +1,111 @@
+package main
+
+import (
+	"database/sql"
+	"encoding/csv"
+	"flag"
+	"log"
+	"os"
+	"strconv"
+
+	_ "github.com/go-sql-driver/mysql"
+)
+
+// Student from Database
+type Student struct {
+	Vorname, Nachname string
+	Matrikelnummer    int
+	StudiengangID     int
+}
+
+var (
+	databaseURL = flag.String("db", "julian:hi@/test", "The Database url")
+)
+
+const (
+	insertQuery = "INSERT INTO Teilnehmer (Nachname, Vorname, Matrnr, Studiengang) VALUES(?,?,?,?)"
+)
+
+// Main Function
+func main() {
+	flag.Parse()
+
+	if flag.NArg() == 0 {
+		log.Fatal("no file(s) given!")
+	}
+
+	// try to open file
+	file, err := os.Open(flag.Arg(0))
+	if err != nil {
+		log.Fatal("could not open file:", err)
+	}
+	defer file.Close()
+
+	reader := csv.NewReader(file)
+
+	defer log.Println("shutdown completed")
+	// list all Database providers
+	log.Println("Database providers:", sql.Drivers())
+
+	// connect to database
+	db, err := sql.Open("mysql", *databaseURL)
+
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer db.Close()
+	log.Println("mysql connection established")
+	// prepare Queries
+	newStudent, err := db.Prepare(insertQuery)
+	if err != nil {
+		log.Fatal("Error preparing statement:", insertQuery+":", err)
+	}
+
+	defer newStudent.Close()
+
+	// init completed
+	defer log.Println("shutting down")
+
+	var (
+		line       []string
+		linenumber = 0
+		count      = 0
+	)
+
+	for ; err == nil; line, err = reader.Read() {
+		linenumber++
+		if len(line) < 4 {
+			log.Println("line", linenumber, "malformed")
+			continue
+		}
+
+		number, err := strconv.Atoi(line[2])
+		if err != nil {
+			log.Println("line", linenumber, ":could not convert ID:"+line[2]+":", err)
+			continue
+		}
+		if number < 0 {
+			log.Println("line", linenumber, ":ID invalid:", number)
+			continue
+		}
+
+		studiengang, err := strconv.Atoi(line[3])
+		if err != nil {
+			log.Println("line", linenumber, ":studiengang could not be converted:", err)
+			continue
+		}
+		if studiengang < 0 || studiengang > 2 {
+			log.Println("line", linenumber, ":Studiengang does not exist:", studiengang)
+			continue
+		}
+
+		if _, err := newStudent.Exec(line[0], line[1], number, studiengang); err != nil {
+			log.Println("line", linenumber, ":could not execute INSERT:", err)
+			continue
+		}
+
+		count++
+	}
+
+	log.Println("done, inserted", count, "records")
+}